Well...you know, EF is really based on the histories of Yuuko and Yuu, so the second season must really explore the context about their historie (the deepest on EF saga), so lets just wait for a good production from Minori, Im sure they wont let their public fall.
Lets just wait...

The wait makes a better impression...but anyway, you cant always have your expectatives on the first episode ;P
You will have to wait each weak for each episode...that would be a long...LONG...really Long wait.

It seems that Yuuko and Yuu know each other when they were high school students. A new girl character is introduced and she is Hirono Nagi. Yuuko is revealed to be Yuu's younger sister but it was not stated whether they are from the same parents or not. Yuuko hates him.